The correct answer is C. CNG.
The calorific value of a fuel is the amount of heat energy released when one unit of the fuel is burned. The calorific value of petrol is 43.2 MJ/kg. The calorific values of methane, kerosene, and LPG are 50.0 MJ/kg, 46.2 MJ/kg, and 46.1 MJ/kg, respectively. Therefore, CNG has the highest calorific value among the given options.
Methane is a gas that is lighter than air and is used as a fuel in natural gas vehicles. Kerosene is a liquid fuel that is used in jet engines and diesel engines. LPG is a gas that is lighter than air and is used as a fuel in cooking and heating appliances.
CNG is a better fuel than petrol because it has a higher calorific value, it is cleaner burning, and it produces fewer emissions.